scholarly journals New insights into the allosteric effects of CO2 and bicarbonate on crocodilian hemoglobin

2021 ◽  
Author(s):  
Naim M. Bautista ◽  
Hans Malte ◽  
Chandrasekhar Natarajan ◽  
Tobias Wang ◽  
Jay F. Storz ◽  
...  
Keyword(s):  
Diffusion Chamber ◽  
Gas Diffusion ◽  
Breath Hold ◽  
Allosteric Control ◽  
Co2 Transport ◽  
Mediated Effects ◽  
Bicarbonate Ions ◽  
The Common ◽  
O2 Delivery ◽  
Positively Charged

Crocodilians are unique among vertebrates in that their hemoglobin (Hb) O2 binding is allosterically regulated by bicarbonate, which forms in the red blood cell upon hydration of CO2. Although known for decades, this remarkable mode of allosteric control has not yet been experimentally verified with direct evidence of bicarbonate binding to crocodilian Hb, probably because of confounding CO2-mediated effects. Here we provide the first quantitative analysis of the separate allosteric effects of CO2 and bicarbonate on purified Hb of the spectacled caiman (Caiman crocodilus). Using thin-layer gas diffusion chamber and Tucker chamber techniques, we demonstrate that both CO2 and bicarbonate bind to Hb with high affinity and strongly decrease Hb-O2 saturation. We propose that both effectors bind to an unidentified positively charged site containing a reactive amino group in the low-O2 affinity T conformation of the Hb. These results provide the first experimental evidence that bicarbonate binds directly to crocodilian Hb and promotes O2 delivery independently of CO2. Using the gas-diffusion chamber, we observed similar effects in Hbs of a phylogenetically diverse set of other caiman, alligator, and crocodile species, suggesting that the unique mode of allosteric regulation by CO2 and bicarbonate evolved >80-100 million years ago in the common ancestor of crocodilians.Our results show a tight and unusual linkage between O2 and CO2 transport in the blood of crocodilians, where build-up of erytrocytic CO2 and bicarbonate ions during breath-hold diving or digestion facilitates O2 delivery, while Hb desaturation facilitates CO2 transport as protein-bound CO2 and bicarbonate.

scholarly journals New insights into the allosteric effects of CO2 and bicarbonate on crocodilian hemoglobin

2021 ◽  
Author(s):  
Naim M. Bautista ◽  
Hans Malte ◽  
Chandrasekhar Natarajan ◽  
Tobias Wang ◽  
Jay F. Storz ◽  
...  
Keyword(s):  
Diffusion Chamber ◽  
Gas Diffusion ◽  
Breath Hold ◽  
Allosteric Control ◽  
Co2 Transport ◽  
Mediated Effects ◽  
Bicarbonate Ions ◽  
The Common ◽  
O2 Delivery ◽  
Positively Charged

Crocodilians are unique among vertebrates in that their hemoglobin (Hb) O2 binding is allosterically regulated by bicarbonate, which forms in the red blood cell upon hydration of CO2. Although known for decades, this remarkable mode of allosteric control has not yet been experimentally verified with direct evidence of bicarbonate binding to crocodilian Hb, probably because of confounding CO2-mediated effects. Here we provide the first quantitative analysis of the separate allosteric effects of CO2 and bicarbonate on Hb of the spectacled caiman (Caiman crocodilus). Using thin-layer gas diffusion chamber and Tucker chamber techniques, we demonstrate that both CO2 and bicarbonate bind to Hb with high affinity and strongly decrease Hb-O2 saturation, and propose that both effectors bind to an unidentified positively charged site containing a reactive amino group in the low-O2 affinity T conformation of the Hb. These results provide the first experimental evidence that bicarbonate binds directly to crocodilian Hb and promotes O2 delivery independently of CO2. Using the gas-diffusion chamber, we observed similar effects in the Hbs of a phylogenetically diverse set of other caiman, alligator, and crocodile species, suggesting that the unique mode of allosteric regulation by CO2 and bicarbonate evolved >80-100 million years ago in the common ancestor of crocodilians. Taken together, our results show a tight and unusual linkage between O2 and CO2 transport in the blood of crocodilians, where build-up of blood CO2 and bicarbonate ions during breath-hold diving or digestion facilitates O2 delivery, while Hb desaturation facilitates CO2 transport as protein-bound CO2 and bicarbonate.

scholarly journals Iota-Carrageenan as an Antiviral Treatment for the Common Cold

2020 ◽  
Vol 14 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Ronald Eccles
Keyword(s):  
Clinical Trials ◽  
Respiratory Tract ◽  
Common Cold ◽  
Antiviral Treatment ◽  
Respiratory Viruses ◽  
Common Disease ◽  
Upper Respiratory Tract ◽  
Good Tolerability ◽  
The Common ◽  
Positively Charged

Introduction: The common cold syndrome of acute upper respiratory tract viral infection is the most common disease among mankind and is an extremely common illness in children. There is a great need for a safe and effective antiviral treatment with minimal side effects. The challenge in developing a treatment is the numerous and varied respiratory viruses that cause this common illness and the need for a treatment with good tolerability and safety. Explanation: All respiratory viruses must reach the cell surface by passing through respiratory fluid and mucus, and this common feature may allow for the development of antivirals that capture viruses during this transit. This article discusses how large polyanionic molecules such as iota-carrageenan may trap positively charged respiratory viruses. Iota-carrageenan is a large polysaccharide molecule which is neither absorbed from the respiratory tract nor metabolised. It, therefore, does not have any pharmacological properties. Iota-carrageenan nasal spray has been shown to reduce the titres of respiratory viruses and to reduce the severity of symptoms in placebo-controlled clinical trials, including children and adults. The results of four clinical trials are presented. Conclusion: Iota-carrageenan is a good candidate as a safe and effective non-specific antiviral treatment for common cold, and more research is justified on polyanionic molecules like carrageenans as antivirals.

Measurement of temporal changes in DLSBCO-3EQ from small alveolar samples in normal subjects

1994 ◽  
Vol 76 (4) ◽  
pp. 1494-1501 ◽  
Author(s):  
G. R. Soparkar ◽  
J. T. Mink ◽  
B. L. Graham ◽  
D. J. Cotton
Keyword(s):  
Hold Time ◽  
Normal Subjects ◽  
Gas Diffusion ◽  
Phase Iii ◽  
Mixing Efficiency ◽  
Breath Holding ◽  
Breath Hold ◽  
Inspiratory Capacity ◽  
Ventilation Inhomogeneity ◽  
Single Breath

The dynamic changes in CO concentration [CO] during a single breath could be influenced by topographic inhomogeneity in the lung or by peripheral inhomogeneity due to a gas mixing resistance in the gas phase of the lung or to serial gradients in gas diffusion. Ten healthy subjects performed single-breath maneuvers by slowly inhaling test gas from functional residual capacity to one-half inspiratory capacity and slowly exhaling to residual volume with target breath-hold times of 0, 1.5, 3, 6, and 9 s. We calculated the three-equation single-breath diffusing capacity of the lung for CO (DLSBCO-3EQ) from the mean [CO] in both the entire alveolar gas sample and in four successive equal alveolar gas samples. DLSBCO-3EQ from the entire alveolar gas sample was independent of breath-hold time. However, with 0 s of breath holding, from early alveolar gas samples DLSBCO-3EQ was reduced and from late alveolar gas samples it was increased. With increasing breath-hold time, DLSBCO-3EQ from the earliest alveolar gas sample rapidly increased, whereas from the last alveolar gas sample it rapidly decreased such that all values from the small alveolar gas samples approached DLSBCO-3EQ from the entire alveolar sample. These changes correlated with ventilation inhomogeneity, as measured by the phase III He concentration slope and the mixing efficiency, and were larger for maneuvers with inspired volumes to one-half inspiratory capacity vs. total lung capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Impact of Impurities in CO2-Fluids on CO2 Transport Process

2006 ◽  
Author(s):  
H. Li ◽  
J. Yan
Keyword(s):  
Thermodynamic Properties ◽  
Critical Point ◽  
Transport Process ◽  
Liquid Equilibrium ◽  
Vapor Liquid Equilibrium ◽  
Motor Carriers ◽  
Co2 Transport ◽  
Process Studies ◽  
The Common ◽  
The Impact

There are four possible transportation means that could be used to deliver CO2: motor carriers, railway carriers, water carriers, and pipeline. The impurities in CO2-fluids have significant impacts on the thermodynamic properties that will further affect the design, operation and cost of CO2 transport. This paper focuses on how impurities in CO2-fluids affect thermodynamic properties, and how the changes of properties affect CO2 transport process. Vapor-liquid equilibrium (VLE), critical point and densities are essential thermodynamic properties for designing a CO2 transport process. Studies on these properties will be carried out for CO2-mixtures based on the combinations of the common impurities such as SO2, H2S, CH4, Ar, O2 and N2. Moreover with a real case of pipeline for CO2 transport, the impact of impurities on transport process will be demonstrated in more details.

Breath-hold diving as a brain survival response

2013 ◽  
Vol 4 (3) ◽  
Author(s):  
Zeljko Dujic ◽  
Toni Breskovic ◽  
Darija Bakovic
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Respiratory Muscles ◽  
Breath Hold ◽  
Diving Response ◽  
Compensatory Mechanisms ◽  
Physiological Adaptations ◽  
O2 Delivery ◽  
World Records ◽  
The Brain

AbstractElite breath-hold divers are unique athletes challenged with compression induced by hydrostatic pressure and extreme hypoxia/hypercapnia during maximal field dives. The current world records for men are 214 meters for depth (Herbert Nitsch, No-Limits Apnea discipline), 11:35 minutes for duration (Stephane Mifsud, Static Apnea discipline), and 281 meters for distance (Goran Čolak, Dynamic Apnea with Fins discipline). The major physiological adaptations that allow breath-hold divers to achieve such depths and duration are called the “diving response” that is comprised of peripheral vasoconstriction and increased blood pressure, bradycardia, decreased cardiac output, increased cerebral and myocardial blood flow, splenic contraction, and preserved O2 delivery to the brain and heart. This complex of physiological adaptations is not unique to humans, but can be found in all diving mammals. Despite these profound physiological adaptations, divers may frequently show hypoxic loss of consciousness. The breath-hold starts with an easy-going phase in which respiratory muscles are inactive, whereas during the second so-called “struggle” phase, involuntary breathing movements start. These contractions increase cerebral blood flow by facilitating left stroke volume, cardiac output, and arterial pressure. The analysis of the compensatory mechanisms involved in maximal breath-holds can improve brain survival during conditions involving profound brain hypoperfusion and deoxygenation.

scholarly journals Computational Biophysical, Biochemical, and Evolutionary Signature of Human R-Spondin Family Proteins, the Member of Canonical Wnt/β-Catenin Signaling Pathway

2014 ◽  
Vol 2014 ◽  
pp. 1-22 ◽  
Author(s):  
Ashish Ranjan Sharma ◽  
Chiranjib Chakraborty ◽  
Sang-Soo Lee ◽  
Garima Sharma ◽  
Jeong Kyo Yoon ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Computational Algorithm ◽  
Biophysical Properties ◽  
Glycosylation Sites ◽  
Peptide Length ◽  
Basic Understanding ◽  
Therapeutic Properties ◽  
The Common ◽  
Canonical Wnt ◽  
Positively Charged

In human, Wnt/β-catenin signaling pathway plays a significant role in cell growth, cell development, and disease pathogenesis. Four human (Rspo)s are known to activate canonical Wnt/β-catenin signaling pathway. Presently, (Rspo)s serve as therapeutic target for several human diseases. Henceforth, basic understanding about the molecular properties of (Rspo)s is essential. We approached this issue by interpreting the biochemical and biophysical properties along with molecular evolution of (Rspo)s thorough computational algorithm methods. Our analysis shows that signal peptide length is roughly similar in (Rspo)s family along with similarity in aa distribution pattern. In Rspo3, four N-glycosylation sites were noted. All members are hydrophilic in nature and showed alike GRAVY values, approximately. Conversely, Rspo3 contains the maximum positively charged residues while Rspo4 includes the lowest. Four highly aligned blocks were recorded through Gblocks. Phylogenetic analysis shows Rspo4 is being rooted with Rspo2 and similarly Rspo3 and Rspo1 have the common point of origin. Through phylogenomics study, we developed a phylogenetic tree of sixty proteins (n=60) with the orthologs and paralogs seed sequences. Protein-protein network was also illustrated. Results demonstrated in our study may help the future researchers to unfold significant physiological and therapeutic properties of (Rspo)s in various disease models.

scholarly journals Evolved increases in hemoglobin-oxygen affinity and the Bohr effect coincided with the aquatic specialization of penguins

2021 ◽  
Vol 118 (13) ◽  
pp. e2023936118
Author(s):  
Anthony V. Signore ◽  
Michael S. Tift ◽  
Federico G. Hoffmann ◽  
Todd. L. Schmitt ◽  
Hideaki Moriyama ◽  
...  
Keyword(s):  
Common Ancestor ◽  
Oxygen Affinity ◽  
Low Ph ◽  
Bohr Effect ◽  
Site Directed Mutagenesis ◽  
Breath Hold ◽  
Directed Mutagenesis ◽  
Hemoglobin Oxygen Affinity ◽  
The Common ◽  
Foraging Time

Dive capacities of air-breathing vertebrates are dictated by onboard O2 stores, suggesting that physiologic specialization of diving birds such as penguins may have involved adaptive changes in convective O2 transport. It has been hypothesized that increased hemoglobin (Hb)-O2 affinity improves pulmonary O2 extraction and enhances the capacity for breath-hold diving. To investigate evolved changes in Hb function associated with the aquatic specialization of penguins, we integrated comparative measurements of whole-blood and purified native Hb with protein engineering experiments based on site-directed mutagenesis. We reconstructed and resurrected ancestral Hb representing the common ancestor of penguins and the more ancient ancestor shared by penguins and their closest nondiving relatives (order Procellariiformes, which includes albatrosses, shearwaters, petrels, and storm petrels). These two ancestors bracket the phylogenetic interval in which penguin-specific changes in Hb function would have evolved. The experiments revealed that penguins evolved a derived increase in Hb-O2 affinity and a greatly augmented Bohr effect (i.e., reduced Hb-O2 affinity at low pH). Although an increased Hb-O2 affinity reduces the gradient for O2 diffusion from systemic capillaries to metabolizing cells, this can be compensated by a concomitant enhancement of the Bohr effect, thereby promoting O2 unloading in acidified tissues. We suggest that the evolved increase in Hb-O2 affinity in combination with the augmented Bohr effect maximizes both O2 extraction from the lungs and O2 unloading from the blood, allowing penguins to fully utilize their onboard O2 stores and maximize underwater foraging time.

Electrophoretic Integration of Polyaniline on NIST Microhotplate for Gas Sensing

2005 ◽  
Vol 876 ◽  
Author(s):  
Guofeng Li ◽  
Steve Semancik
Keyword(s):  
Gas Sensing ◽  
Colloidal Suspension ◽  
Gas Diffusion ◽  
Acid Solutions ◽  
Great Precision ◽  
Sensor Performance ◽  
Polyaniline Films ◽  
Controlled Deposition ◽  
And Control ◽  
Positively Charged

AbstractWe present a method for controlled deposition of polyaniline from a colloidal suspension. Stable suspensions of polyaniline colloids were formed by dispersing polyaniline/formic-acid solutions into acetonitrile. It is demonstrated that the positively charged polyaniline colloids can be electrophoretically patterned onto microfabricated device features with great precision and control. Futhermore, the electrophoretically deposited polyaniline films reveal a nanoporous morphology, which greatly enhances the gas diffusion that leads to improved sensor performance.

Plants possibility to control soil gas exchanges via mucilage

2020 ◽  
Author(s):  
Adrian Haupenthal ◽  
Jonas Bentz ◽  
Mathilde Brax ◽  
Klaus Schuetzenmeister ◽  
Hermann Jungkunst ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Oxygen Diffusion ◽  
Diffusion Processes ◽  
Pore Space ◽  
Diffusion Chamber ◽  
Gas Diffusion ◽  
Control Soil ◽  
Pore System ◽  
Gas Exchanges ◽  
Dry Soil

<p>Gaseous matter exchanges in soil are determined by the connectivity of the pore system which is easily clogged by fresh root exudates. However, it remains unclear how a hydrogel (e.g. mucilage) affects soil pore tortuosity when drying. The aim of this study is to obtain a better understanding of gas diffusion processes in the rhizosphere by explaining patterns formed by drying mucilage.</p><p>We measured oxygen diffusion through a soil-mucilage mixture after drying using a diffusion chamber experiment. Therefore we mixed soil with different particle size with various amounts of mucilage. Afterwards we saturated the soil and measured the gas diffusion coefficient during drying.</p><p>We found that mucilage decreases gas diffusion coefficient in dry soil without significantly altering bulk density and porosity. Electron microscopy indicate that during drying mucilage forms filaments and interconnected structures throughout the pore space. Exudation of mucilage may be a plant possibility to actively alter gas diffusion in soil.</p>

scholarly journals Sequential determination of free and total cyanide by flow injection

1999 ◽  
Vol 21 (1) ◽  
pp. 23-26 ◽  
Author(s):  
Maria Angélica Bonadiman Martin ◽  
Edgard Moreira Ganzarolli ◽  
Arilson Lehmkuhl ◽  
Ivan Gonçlves de Souza ◽  
Roldão Roosevelt Urzêdo de Queiróz
Keyword(s):  
Flow Injection ◽  
Direct Detection ◽  
Chemical Species ◽  
Diffusion Chamber ◽  
Gas Diffusion ◽  
Ion Selective Electrode ◽  
Injection System ◽  
Selective Electrode ◽  
Sequential Determination

This study presents a flow injection system for the sequential determination of free (CN-) and total (CN-+ HCN) cyanide using a potentiometric method which employs two different processes for the determination of these two chemical species. The first process is based on direct detection of CN-using an ion-selective electrode for cyanide. In the second process, the sample is mixed with acid, and the released HCN is transferred across a PTFE membrane. The flow system employs three solenoid valves, a gas diffusion chamber, an ion-selective electrode, a potentiometer, and a computer with an AID conversion card. A Turbo Pascal®computer program automatically performs all the steps involved in data acquisition and processing. The standard deviation for the results obtained with the proposed method was 0.5%.

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